The present invention relates generally to a superconductive magnet (such as, but not limited to, a helium-cooled and/or cryocooler-cooled superconductive magnet) used to generate a high magnetic field as part of a magnetic resonance imaging (MRI) system, and more particularly to such a magnet support structure in an MRI magnet having a closed design.
MRI systems employing superconductive or other type magnets are used in various fields such as medical diagnostics. Known superconductive magnets include liquid-helium cooled and cryocooler-cooled superconductive magnets. Typically, for a helium-cooled magnet, the superconductive coil assembly includes a superconductive main coil which is at least partially immersed in liquid helium contained in a helium dewar which is surrounded by a dual thermal shield which is surrounded by a vacuum enclosure. In a conventional cryocooler-cooled magnet, the superconductive main coil is surrounded by a thermal shield which is surrounded by a vacuum enclosure, and the cryocooler coldhead is externally mounted to the vacuum enclosure with the coldhead""s first stage in thermal contact with the thermal shield and with the coldhead""s second stage in thermal contact with the superconductive main coil. Nb-Ti superconductive coils typically operate at a temperature of generally 4 Kelvin, and Nb-Sn superconductive coils typically operate at a temperature of generally 10 Kelvin.
Known superconductive magnet designs include closed magnets and open magnets. Closed magnets typically have a single, tubular-shaped superconductive coil assembly having a bore. The superconductive coil assembly includes several radially aligned and longitudinally spaced-apart superconductive main coils each carrying a large, identical electric current in the same direction. The closed MRI magnet typically has a single superconductive coil assembly including a generally toroidal-shaped magnet support structure surrounding a bore and having a generally longitudinally extending axis. The magnet support structure also includes a pair of longitudinally spaced apart, generally identical, and generally annular-shaped superconductive main coils each generally coaxially aligned with the longitudinally extending axis. Each main coil typically carries a generally identical first electric current in an identical first electric-current direction. Each main coil is located within the superconductive coil assembly, and each main coil has a longitudinally outermost portion. The main coils are thus designed to create a magnetic field of high uniformity within a spherical imaging volume centered within the magnet""s bore where the object to be imaged is placed. Closed MRI magnets tend to have a relatively long axial (i.e., longitudinal) length to accommodate the number of main superconductive coils needed to achieve a homogeneous imaging volume. The relatively long axial length tends to create claustrophobic feelings in patients, especially in the case of whole-body magnets.
What is needed is a magnet support structure for a closed MRI magnet that is designed to have a relatively short axial (i.e., longitudinal) length to overcome the claustrophobic feelings of patients, while simultaneously providing physicians at least some patient access.
The present invention provides a magnet support structure. A cylindrical portion comprises a plurality of laminated composite layers concentrically assembled to one another along a longitudinal axis. An integral left flange is comprised of the laminated composite layers concentrically assembled with respect to a left flange axis. The left flange axis is perpendicular to the longitudinal axis. An integral right flange is comprised of the laminated composite layers concentrically assembled with respect to a right flange axis. The right flange axis is perpendicular to the longitudinal axis. A method for fabricating the magnet support structure comprises concentrically assembling the plurality of laminated composite layers along the longitudinal axis forming the cylindrical portion, concentrically assembling the laminated composite layers with respect to the left flange axis forming the integral left flange, and concentrically assembling the laminated composite layers with respect to the right flange axis forming the integral right flange.